President Trump’s historically low approval ratings provide Democrats legitimate reasons for optimism about their prospects in the 2018 elections, especially in the House. But that confidence rests on a contradiction: Minorities and Millennials, the groups most alienated from Trump, are traditionally the constituencies least likely to vote in midterm elections.
The contrast between the electorate’s composition in presidential and midterm elections has confounded Democrats since the 1990s. Over the past two decades, the party has grown more reliant on a coalition revolving around college-educated whites (especially women), minorities, and Millennials. That new configuration has left Democrats with a boom-and-bust coalition, because the latter two groups are much more likely to vote in presidential elections than midterms; that off-year falloff has been particularly severe among young people. As those Democratic-leaning groups recede in midterms, the older whites who increasingly favor the GOP cast a larger share of ballots.
That dynamic helped fuel the GOP sweeps in both the 2010 and 2014 contests under former President Barack Obama, and offers a warning for the next one. “If the 2018 electorate resembles a typical midterm electorate, Democrats won’t take back the House,” said Tom Bonier, chief executive of the Democratic voter-targeting firm TargetSmart. “The question of millennial turnout is the biggest question to that end, and it will remain an open question until Election Day 2018.”